The present invention relates to a vacuum capacitor for various circuits such as an oscillating circuit of a super power oscillator, an RF power circuit of a semiconductor manufacturing apparatus, and a tank circuit of an induction heating apparatus, and more particularly, to a bellows for use in the vacuum capacitor.
Vacuum capacitors are broadly divided into a vacuum fixed capacitor wherein a capacitance value is fixed and a vacuum variable capacitor wherein a capacitance value can be varied.
The characteristics required of the vacuum variable capacitor are lower power loss, less heat generation during energization, longer life, and the like. As will be described hereinafter in detail, the vacuum variable capacitor comprises a bellows which follows a movable electrode to maintain the hermeticity of the inside of a vacuum vessel and which serves as a current path between a movable-electrode support plate and a movable side-end plate. Thus, the material of the bellows exerts a great influence on the required characteristics.